After finishing Serenity there was a wrap party where the full gag reel was shown to everyone's amusement, then the credits came on and all of a sudden two words appeared "For Jewel".

Out on the screen, a puppet* Caleb (Nathan's character on "Buffy") entered, like the Mutant Enemy "Grr Arrg"-monster usually does, and flipped the finger.

The puppet had been made by a fan called Clare, for her costume at the fancy dress at Fusion. Because Nathan had liked "Wee Caleb" so much, she had given it to him. And when he used it for his prank on Jewel he also gave Clare a copy of the footage.

* Thanks Andy for correcting me on the animated/puppet Caleb misshap. As well as for sharing the background for the puppet.

:: Disclaimer ::

I am in no way afilliated with Jewel Staite or Nathan Fillion, though if they should wish it, I would love to be.